The concentration of blood of glycosylated hemoglobin has been shown to be a useful tool in assessing the degree of glucose intolerance in diabetic subjects and in monitoring the efficacy of diabetes treatment. An electrophoretic method (Corning Medical and Scientific, Medford, MA) of separating glycosylated from nonglycosylated hemoglobin has been implemented in the longitudinal study of diabetes in the Pima Indians.